Turbine cooling apparatus

ABSTRACT

A turbine cooling apparatus of an embodiment includes a cooling air supply unit and a control unit The control unit controls an operation of the cooling air supply unit during a turning operation. Here, the control unit controls the operation of the cooling air supply unit to make the cooling air supply unit supply the cooling air at a previously determined flow rate. Thereafter, the control unit controls the operation of the cooling air supply unit based on at least either of a result obtained by measuring differential expansion between a turbine rotor and a turbine casing, and a result obtained by measuring a temperature difference between an inner peripheral surface of a steam chamber positioned at an entrance of a steam flow path through which steam flows in the turbine casing and an outer peripheral surface of the steam chamber.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2014-264061, filed on Dec. 26, 2014; the entire contents of all of which are incorporated therein by reference.

FIELD

Embodiments described herein relate generally to a turbine cooling apparatus.

BACKGROUND

A turbine cooling apparatus is used for forcibly cooling a steam turbine at a time of inspection and the like, for example. The turbine cooling apparatus performs cooling by supplying cooling air to an inner part of a turbine casing during a turning operation which is performed after a normal operation of the steam turbine is stopped.

The turbine cooling apparatus supplies, in a double-structured turbine casing including an inner casing and an outer casing, for example, cooling air to each of a space between the inner casing and the outer casing, and an inner space of the inner casing. Here, a flow rate of the cooling air is adjusted based on, for example, a measurement result of differential expansion between the turbine casing and a turbine rotor housed in the turbine casing, and the like.

However, in a conventional turbine cooling apparatus, it is sometimes difficult to cool a steam turbine in a short period of time. For this reason, a state where the above-described differential expansion and the temperature difference are out of previously determined ranges, is sometimes created. As a result of this, an alarm is sometimes issued.

Therefore, a problem to be solved by the present invention is to provide a turbine cooling apparatus capable of easily realizing cooling of a steam turbine in a short period of time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically illustrating a steam turbine system according to a first embodiment.

FIG. 2 is a sectional view illustrating a high-pressure turbine in the steam turbine system according to the first embodiment.

FIG. 3 is a view illustrating a first tubular body in the steam turbine system according to the first embodiment.

FIG. 4 is a flow chart illustrating an outline of an operation when a turbine cooling apparatus cools a steam turbine in the steam turbine system according to the first embodiment.

FIG. 5 is a view schematically illustrating a steam turbine system according to a second embodiment.

FIG. 6 is a view schematically illustrating a steam turbine system according to a third embodiment.

FIG. 7 is a sectional view illustrating a high-pressure turbine in the steam turbine system according to the third embodiment.

FIG. 8 is a view illustrating a cooling air discharge pipe and a first tubular body in a steam turbine system 1 according to the first embodiment.

DETAILED DESCRIPTION

A turbine cooling apparatus of an embodiment includes a cooling air supply unit and a control unit, and cools a steam turbine in which a turbine rotor is housed in an inner part of a turbine casing. The cooling air supply unit supplies cooling air to the inner part of the turbine casing. The control unit controls an operation of the cooling air supply unit during a turning operation. Here, the control unit controls the operation of the cooling air supply unit to make the cooling air supply unit supply the cooling air at a previously determined flow rate. Thereafter, the control unit controls the operation of the cooling air supply unit based on at least either of a result obtained by measuring differential expansion between the turbine rotor and the turbine casing, and a result obtained by measuring a temperature difference between an inner peripheral surface of a steam chamber positioned at an entrance of a steam flow path through which steam flows in the turbine casing and an outer peripheral surface of the steam chamber.

Embodiments will be described with reference to the drawings.

First Embodiment [A] Configuration

FIG. 1 is a view schematically illustrating a steam turbine system 1 according to a first embodiment. In FIG. 1, a flow path of cooling air supplied to a steam turbine 10 as a cooling medium is indicated by an arrow mark of solid line, and a part of flow paths of steam supplied to the steam turbine 10 as a working medium is omitted appropriately.

As illustrated in FIG. 1, the steam turbine system 1 has a steam turbine 10 and a turbine cooling apparatus 50.

[A-1] Steam Turbine 10

In the steam turbine system 1, the steam turbine 10 includes a high-pressure turbine 11, an intermediate-pressure turbine 12, a first low-pressure turbine 13, and a second low-pressure turbine 14.

[A-1-1] High-Pressure Turbine 11

In the steam turbine 10, the high-pressure turbine 11 has steam introducing parts 111 a and 111 b, and a steam discharge part 112, as illustrated in FIG. 1. In the high-pressure turbine 11, the steam introducing parts 111 a and 111 b are connected to main steam pipes F30 a and F30 b. The steam discharge part 112 is connected to a low-temperature reheat steam pipe F11.

When a normal operation is performed in the steam turbine 10, steam generated by a heater (whose illustration is omitted) of a boiler (whose illustration is omitted) flows through the main steam pipes F30 a and F30 b after sequentially passing through a main steam stop valve 20 and a steam control valve 30, and flows into the steam introducing parts 111 a and 111 b of the high-pressure turbine 11 as a working medium. Here, the steam is branched at a branch portion J30 b to flow through the main steam pipes F30 a and F30 b, thereby flowing into each of the plurality of steam introducing parts 111 a and 111 b. Further, in the high-pressure turbine 11, the steam performs its work and then is discharged from the steam discharge part 112 to the low-temperature reheat steam pipe F11.

FIG. 2 is a sectional view illustrating the high-pressure turbine 11 in the steam turbine system 1 according to the first embodiment. FIG. 2 illustrates a cross section of a vertical plane (xz plane) defined by a direction along a rotation axis AX (x direction) in the horizontal direction (x direction, y direction), and a vertical direction (z direction).

As illustrated in FIG. 2, the high-pressure turbine 11 has a turbine casing 110 and a turbine rotor 300. The high-pressure turbine 11 is a multistage axial flow turbine, in which a plurality of turbine stages 400 each including a stationary blade cascade 401 and a rotor blade cascade 402 are arranged along the rotation axis AX, in the inner part of the turbine casing 110, and when steam expands and performs its work in the plurality of turbine stages 400, the turbine rotor 300 rotates around the rotation axis AX. The high-pressure turbine 11 is of single-flow discharge type, and it is configured such that steam flows from the steam introducing parts 111 a and 111 b provided on one end side of the turbine rotor 300 toward the steam discharge part 112 provided on the other end side of the turbine rotor to be exhausted.

In the high-pressure turbine 11, the turbine casing 110 is double-structured, for example, and has an inner casing 201 and an outer casing 202.

In the turbine casing 110, the inner casing 201 houses a part of the turbine rotor 300 in an inner part thereof. Along with this, the inner casing 201 supports the stationary blade cascades 401 at its inner peripheral surface. In the stationary blade cascade 401, a plurality of stationary blades are arranged, at intervals, in a circumferential direction of the turbine rotor 300. The inner casing 201 includes an upper half part of inner casing 211 and a lower half part of inner casing 212, and is configured by combining both of the parts.

In the turbine casing 110, the outer casing 202 houses the inner casing 201 in an inner part thereof. The outer casing 202 has an upper half part of outer casing 221 and a lower half part of outer casing 222, and is configured by combining both of the parts.

In the turbine casing 110, the steam introducing parts 111 a and 111 b include first steam inlet portions 201 a and 201 b, and second steam inlet portions 202 a and 202 b.

The first steam inlet portions 201 a and 201 b are openings penetrating between the inner part and the outer part of the inner casing 201, and are formed on the upper half part of inner casing 211 and the lower half part of inner casing 212, respectively.

The second steam inlet portions 202 a and 202 b are openings penetrating between the inner part and the outer part of the outer casing 202, and are formed on the upper half part of outer casing 221 and the lower half part of outer casing 222, respectively.

The first steam inlet portions 201 a and 201 b, and the second steam inlet portions 202 a and 202 b are respectively provided so as to be coaxially arranged in a radial direction of the turbine rotor 300, and a gap is interposed between the first steam inlet portion 201 a and the second steam inlet portion 202 a, and between the first steam inlet portion 201 b and the second steam inlet portion 202 b. Each of the first steam inlet portions 201 a and 201 b and the second steam inlet portions 202 a and 202 b is a flow path having a circular cross section, the first steam inlet portion 201 a and the second steam inlet portion 202 a are connected via a sleeve 500 a, and the first steam inlet portion 201 b and the second steam inlet portion 202 b are connected via a sleeve 500 b.

In the turbine casing 110, the steam discharge part 112 is an opening penetrating between the inner part and the outer part of the outer casing 202.

In the high-pressure turbine 11, the turbine rotor 300 is a rod-shaped body (shaft) having a columnar shape, and is configured to be rotated, together with the rotor blade cascades 402 disposed in the turbine rotor 300, by a working fluid F which flows in an axial direction along the rotation axis AX. Here, the turbine rotor 300 has the rotation axis AX extending in the horizontal direction (x direction), and penetrates through the turbine casing 110. The turbine rotor 300 has one end part and the other end part which are respectively supported in a rotatable manner by bearings (whose illustration is omitted). The turbine rotor 300 supports the rotor blade cascades 402 at its outer peripheral surface. The rotor blade cascade 402 has a plurality of rotor blades arranged, at intervals, in the circumferential direction of the turbine rotor 300.

The high-pressure turbine 11 has, other than the above elements, a first tubular body 250 a and a second tubular body 250 b. The first tubular body 250 a and the second tubular body 250 b are respectively straight tubular bodies, and are disposed in the turbine casing 110 so that tube axes thereof extend along the radial direction of the turbine rotor 300. Here, the first tubular body 250 a is inserted into a through hole 113 a formed on the outer casing 202 and a through hole 114 a formed on the inner casing 201, and the second tubular body 250 b is inserted into a through hole 113 b formed on the outer casing 202 and a through hole 114 b formed on the inner casing 201.

Concretely, the first tubular body 250 a is a balance plug attachment tube to which a balance plug (whose illustration is omitted) is attached. The first tubular body 250 a is supported by being inserted into each of the through hole 113 a formed on the upper half part of outer casing 221, and the through hole 114 a formed on the upper half part of inner casing 211.

On the contrary, the second tubular body 250 b is a thermocouple protection tube which houses thermocouples (whose illustration is omitted) in an inner part thereof. The second tubular body 250 b is supported by being inserted into each of the through hole 113 b formed on the lower half part of outer casing 222, and the through hole 114 b formed on the lower half part of inner casing 212.

FIG. 3 is a view illustrating the first tubular body 250 a in the steam turbine system 1 according to the first embodiment. FIG. 3 illustrates a state where the tubular body is seen from a direction along the rotation axis AX (x direction).

As illustrated in FIG. 3, the first tubular body 250 a has cooling air releasing ports H250 a formed thereon. The cooling air releasing ports H250 a are formed on the first tubular body 250 a so as to penetrate along the rotation axis AX of the turbine rotor 300 (x direction). The number of the cooling air releasing ports H250 a is plural, and the cooling air releasing ports H250 a are arranged along the tube axis of the first tubular body 250 a (z direction in FIG. 3). The second tubular body 250 b has cooling air releasing ports H250 b (refer to FIG. 2), in a similar manner to the first tubular body 250 a.

Although details will be described later, in the present embodiment, when a turning operation is conducted in the steam turbine system 1, cooling air is supplied to the high-pressure turbine 11 from the turbine cooling apparatus 50 (refer to FIG. 1), to thereby cool the high-pressure turbine 11. Here, the supplied cooling air flows into the inner part of the inner casing 201 via the steam introducing parts 111 a and 111 b. Further, the flowed cooling air flows through the inner part of the inner casing 201, and then is discharged to the outside from the steam discharge part 112. Specifically, the cooling air flows through a steam flow path through which steam flows as a working medium in the turbine casing 110 of the high-pressure turbine 11.

Along with this, in the present embodiment, the cooling air supplied from the turbine cooling apparatus 50 flows into a space between the inner casing 201 and the outer casing 202 via the cooling air releasing ports H250 a formed on the first tubular body 250 a, and the cooling air releasing ports H250 b formed on the second tubular body 250 b. Further, the cooling air flows through the space between the inner casing 201 and the outer casing 202, and then is discharged to the outside from the steam discharge part 112. Specifically, the cooling air flows through a space positioned outside the steam flow path, in the inner part of the turbine casing 110 which forms the high-pressure turbine 11.

Note that in the high-pressure turbine 11, a differential expansion measuring unit (whose illustration is omitted) measuring differential expansion between the turbine rotor 300 and the turbine casing 110 is disposed, other than the above elements. The differential expansion measuring unit is, for example, a potentiometer, and is disposed in the turbine casing 110. The differential expansion measuring unit is configured to measure the differential expansion by detecting a gap between a sensor target of the turbine rotor 300 and the differential expansion measuring unit, for example. A result of the differential expansion measured by the differential expansion measuring unit is output, as actual measured data D10, to the turbine cooling apparatus 50.

Further, in the high-pressure turbine 11, there is disposed a temperature difference measuring unit (whose illustration is omitted) measuring a temperature difference between an inner peripheral surface of a steam chamber positioned at an entrance of a steam flow path in which the turbine stages are arranged, in the inner part of the inner casing 201 which forms the turbine casing 110, and an outer peripheral surface of the steam chamber (metal temperature difference of inner and outer surfaces of steam chamber). The temperature difference measuring unit is, for example, a temperature sensor including thermocouples, and is housed in the second tubular body 250 b being the thermocouple protection tube. In the temperature difference measuring unit (whose illustration is omitted), a plurality of the thermocouples are disposed so as to measure the above-described temperature difference by detecting a temperature of the inner peripheral surface of the inner casing 201 which forms the turbine casing 110, and detecting a temperature of the outer peripheral surface of the inner casing 201. A result of the temperature difference measured by the temperature difference measuring unit is output, as actual measured data D10, to the turbine cooling apparatus 50.

[A-1-2] Intermediate-Pressure Turbine 12

In the steam turbine 10, the intermediate-pressure turbine 12 has a steam introducing part 121 and steam discharge parts 122 a and 122 b, as illustrated in FIG. 1. In the intermediate-pressure turbine 12, the steam introducing part 121 is connected to a high-temperature reheat steam pipe F40, and the steam discharge parts 122 a and 122 b are connected to crossover pipes F12 a and F12 b.

When the normal operation is conducted in the steam turbine 10, the steam discharged from the high-pressure turbine 11 flows through the high-temperature reheat steam pipe F40 by passing through a reheat steam combination valve 40, and flows into the steam introducing part 121 of the intermediate-pressure turbine 12. The steam discharged from the high-pressure turbine 11 is reheated by a reheater (whose illustration is omitted) of a boiler (whose illustration is omitted), and then flows into the intermediate-pressure turbine 12 as a working medium. The steam performs its work in the intermediate-pressure turbine 12, and then is discharged from the steam discharge parts 122 a and 122 b to the crossover pipes F12 a, F12 b, and F12 c.

As can be understood from FIG. 1, the intermediate-pressure turbine 12 is of double-flow discharge type, in which the steam flows from the steam introducing part 121 provided at a center part of the turbine in a direction along a rotation axis of a turbine rotor (whose illustration is omitted) toward the steam discharge part 122 a provided on one end side of the turbine and the steam discharge part 122 b provided on the other end side of the turbine, to be exhausted.

Although the illustration is omitted, the intermediate-pressure turbine 12 is a multistage axial flow turbine, in a similar manner to the high-pressure turbine 11, and in an inner part of a turbine casing (whose illustration is omitted), a plurality of turbine stages (whose illustration is omitted) are arranged along the rotation axis.

The turbine casing of the intermediate-pressure turbine 12 is double-structured, for example, in a similar manner to the high-pressure turbine 11, and has an inner casing (whose illustration is omitted) and an outer casing (whose illustration is omitted). The inner casing houses the turbine rotor in an inner part thereof. The inner casing includes an upper half part of inner casing (whose illustration is omitted) and a lower half part of inner casing (whose illustration is omitted), and is configured by combining both of the parts. The outer casing houses the inner casing in an inner part thereof. The outer casing has an upper half part of outer casing (whose illustration is omitted) and a lower half part of outer casing (whose illustration is omitted), and is configured by combining both of the parts.

In the intermediate-pressure turbine 12, the steam introducing part 121 is an opening penetrating through the lower half part of inner casing and the lower half part of outer casing, and is a flow path which introduces the steam into the inner part of the inner casing. The steam discharge parts 122 a and 122 b are openings penetrating between the inner part and the outer part of the upper half part of outer casing, and are flow paths which discharge the steam flowed from the inner part of the inner casing to the outside.

As illustrated in FIG. 1, the intermediate-pressure turbine 12 is provided with, other than the above elements, a plurality of through holes 123 a, 123 b, 124 a, and 124 b. The plurality of through holes 123 a, 123 b, 124 a, and 124 b are formed to penetrate through the lower half part of outer casing. Here, the plurality of through holes 123 a, 123 b, 124 a, and 124 b are disposed so as to be arranged, at intervals, in the direction along the rotation axis of the turbine rotor. Specifically, the plurality of through holes 123 a and 124 a are arranged from the center part to the one end side, and the plurality of through holes 123 b and 124 b are arranged from the center part to the other end side.

Although details will be described later, in the present embodiment, when the turning operation is conducted in the steam turbine system 1, cooling air is supplied to the intermediate-pressure turbine 12 from the turbine cooling apparatus 50, to thereby cool the intermediate-pressure turbine 12, in a similar manner to the high-pressure turbine 11. Here, the cooling air flows into the inner part of the inner casing via the steam introducing part 121. Further, the flowed cooling air flows through the inner part of the inner casing, and then is discharged to the outside from the steam discharge parts 122 a and 122 b.

Along with this, in the present embodiment, the cooling air supplied from the turbine cooling apparatus 50 flows into a space between the inner casing and the outer casing via the plurality of through holes 123 a, 123 b, 124 a, and 124 b. Further, the cooling air flows through the space between the inner casing and the outer casing, and then is discharged to the outside from the steam discharge parts 122 a and 122 b.

Note that in the intermediate-pressure turbine 12, a differential expansion measuring unit (whose illustration is omitted) measuring differential expansion between the turbine rotor and the turbine casing is disposed, other than the above elements, in a similar manner to the high-pressure turbine 11. Further, in the intermediate-pressure turbine 12, there is disposed a temperature difference measuring unit (whose illustration is omitted) measuring a temperature difference between an inner part of a steam chamber positioned at an entrance of a steam flow path through which the steam flows, in the inner part of the turbine casing, and an outer part of the steam chamber. A result of the differential expansion between the turbine rotor and the turbine casing measured by the differential expansion measuring unit, and a result of the temperature difference between the inner part and the outer part of the steam chamber measured by the temperature difference measuring unit are respectively output, as actual measured data D10, to the turbine cooling apparatus 50.

[A-1-3] First Low-Pressure Turbine 13, Second Low-Pressure Turbine 14

In the steam turbine 10, the first low-pressure turbine 13 has a steam introducing part 131, and steam discharge parts 132 a and 132 b, as illustrated in FIG. 1. In the first low-pressure turbine 13, the steam introducing part 131 is connected to the crossover pipe F12 c, and the steam discharge parts 132 a and 132 b are connected to pipe parts F13 a and F13 b.

In a similar manner to the first low-pressure turbine 13, the second low-pressure turbine 14 has a steam introducing part 141, and steam discharge parts 142 a and 142 b. In the second low-pressure turbine 14, the steam introducing part 141 is connected to the crossover pipe F12 a, and the steam discharge parts 142 a and 142 b are connected to pipe parts F14 a and F14 b.

When the normal operation is conducted in the steam turbine 10, the steam discharged from the intermediate-pressure turbine 12 flows through the crossover pipes F12 a, F12 b, and F12 c to flow into the steam introducing parts 131 and 141 of the first low-pressure turbine 13 and the second low-pressure turbine 14 as a working medium. Here, in the crossover pipes F12 a, F12 b, and F12 c, the steams discharged from the intermediate-pressure turbine 12 are joined at a joint point J12 a, and then branched at a branch point J12 b, to thereby flow into each of the steam introducing part 131 of the first low-pressure turbine 13 and the steam introducing part 141 of the second low-pressure turbine 14. The steams perform their works in the first low-pressure turbine 13 and the second low-pressure turbine 14, and then are discharged from the steam discharge parts 132 a, 132 b, 142 a, and 142 b. The steam discharged from each of the first low-pressure turbine 13 and the second low-pressure turbine 14 flows into a steam condenser 60 to be condensed.

As can be understood from FIG. 1, each of the first low-pressure turbine 13 and the second low-pressure turbine 14 is of double-flow discharge type, in a similar manner to the intermediate-pressure turbine 12, in which the steam flows from the steam introducing parts 131 and 141 provided at center parts of the respective turbines in a direction along rotation axes of turbine rotors (whose illustration is omitted) toward the steam discharge parts 132 a and 142 a provided on one end side of the respective turbines and the steam discharge parts 132 b and 142 b provided on the other end side of the respective turbines, to be exhausted.

Although the illustration is omitted, each of the first low-pressure turbine 13 and the second low-pressure turbine 14 is a multistage axial flow turbine, in a similar manner to the high-pressure turbine 11 and the intermediate-pressure turbine 12, and in an inner part of each turbine casing (whose illustration is omitted), a plurality of turbine stages (whose illustration is omitted) are arranged along the rotation axis.

Although details will be described later, in the present embodiment, when the turning operation is conducted in the steam turbine system 1, cooling air is supplied to each of the first low-pressure turbine 13 and the second low-pressure turbine 14 from the turbine cooling apparatus 50, to thereby cool each of the turbines, in a similar manner to the high-pressure turbine 11 and the intermediate-pressure turbine 12. Here, the cooling air flows into the inner part of each of the turbine casings via the steam introducing parts 131 and 141. Further, the flowed cooling air flows through the inner part of each of the turbine casings, and then is discharged to the outside from the steam discharge parts 132 a, 132 b, 142 a and 142 b.

[A-2] Turbine Cooling Apparatus 50

In the steam turbine system 1, the turbine cooling apparatus 50 includes a cooling air supply unit 51 and a control unit 52 as illustrated in FIG. 1, and is configured to cool the steam turbine 10.

[A-2-1] Cooling Air Supply Unit 51 (Cooling Air Supply)

In the turbine cooling apparatus 50, the cooling air supply unit 51 has an air blowing section 511 and a cooling air pipe system 512. The cooling air supply unit 51 supplies, during the turning operation which is performed after the normal operation of the steam turbine is stopped, cooling air blown by the air blowing section 511 to the inner part of the turbine casing of the steam turbine 10 via the cooling air pipe system 512, to thereby forcibly cool the steam turbine 10.

In the present embodiment, the cooling air supply unit 51 supplies cooling air to the inner part of the turbine casing 110 of the high-pressure turbine 11 (refer to FIG. 2). Here, the cooling air supply unit 51 supplies cooling air to the inner part of the inner casing 201 of the high-pressure turbine 11, and it also supplies cooling air to the space between the inner casing 201 and the outer casing 202.

Further, the cooling air supply unit 51 supplies cooling air to the inner part of the turbine casing (whose illustration is omitted) of the intermediate-pressure turbine 12. Here, the cooling air supply unit 51 supplies cooling air to the inner part of the inner casing (whose illustration is omitted) of the intermediate-pressure turbine 12, and it also supplies cooling air to the space between the inner casing and the outer casing (whose illustration is omitted).

Further, the cooling air supply unit 51 supplies cooling air to the inner part of the turbine casing (whose illustration is omitted) of the first low-pressure turbine 13, and it also supplies cooling air to the inner part of the turbine casing (whose illustration is omitted) of the second low-pressure turbine 14.

[A-2-1-1] Air Blowing Section 511

In the cooling air supply unit 51, the air blowing section 511 includes an air blower (whose illustration is omitted), for example.

In the air blowing section 511, air blown by the air blower is sent, as cooling air, to the cooling air pipe system 512.

[A-2-1-2] Cooling Air Pipe System 512

In the cooling air supply unit 51, the cooling air pipe system 512 includes a plurality of pipe parts F51, F511 to F514, F521 to F525, F13 a, F13 b, F14 a, and F14 b, a plurality of manual valves V51, V511 to V514, V521 to V525, V13 a, V13 b, V14 a, and V14 b, and a plurality of automatic valves M51, M511, and M521 to M523.

In the cooling air pipe system 512, each of the plurality of pipe parts F51, F511 to F514, F521 to F525, F13 a, F13 b, F14 a, and F14 b is a flow path through which cooling air blown by the air blowing section 511 flows, and is formed by using a pipe.

The pipe part F51 (a first pipe part) has one end connected to the air blowing section 511, and the other end connected to a connection point J30 a of the main steam pipe F30 a. In the pipe part F51, a plurality of connection points J51 a to J51 d are sequentially provided from one end to the other end. In the pipe part F51, the automatic valve M51 and the manual valve V51 are sequentially disposed, at a position between the other end and the connection point J51 d provided at a position closest to the other end side, from the one end to the other end.

The pipe part F511 (a second pipe part) has one end connected to the connection point J51 d provided at the position closest to the other end side of the pipe part F51 (the first pipe part). Further, the pipe part F511 has the other end connected to the through hole 113 a of the high-pressure turbine 11. In the pipe part F511, a connection point J511 is provided at a position between the one end and the other end. At a position between the one end and the connection point J511 of the pipe part F511, the automatic valve M511 is disposed. Further, at a position between the other end and the connection point J511 of the pipe part F511, the manual valve V511 is disposed.

The pipe part F512 (a third pipe part) has one end connected to the connection point J511 of the pipe part F511 (the second pipe part). Further, the pipe part F512 has the other end connected to the through hole 113 b of the high-pressure turbine 11. At a position between the one end and the other end of the pipe part F512, the manual valve V512 is disposed.

The pipe part F513 (a fourth pipe part) has one end connected to a connection point J11 of the low-temperature reheat steam pipe F11. At a position between the one end and the other end of the pipe part F513, a connection point J513 is provided. At a position between the one end and the other end of the pipe part F513, the manual valve V513 is disposed. The manual valve V513 is closed.

The pipe part F514 (a fifth pipe part) has one end connected to the connection point J513 of the pipe part F513 (the fourth pipe part). Further, the pipe part F514 has the other end opened to the outside. In the pipe part F514, a plurality of connection points J514 a to J514 d are sequentially provided from the one end to the other end. At a position between the one end and the connection point J514 a provided at a position closest to the one end side of the pipe part F514, the manual valve V514 is disposed.

The pipe part F521 (a sixth pipe part) has one end connected to the connection point J51 c provided at the second position from the other end side of the pipe part F51 (the first pipe part). Further, the pipe part F521 has the other end connected to a connection point J40 of the high-temperature reheat steam pipe F40. At a position between the one end and the other end of the pipe part F521, the automatic valve M521 and the manual valve V521 are sequentially disposed from the one end to the other end.

The pipe part F522 (a seventh pipe part) has one end connected to the connection point J51 b provided at the third position from the other end side of the pipe part F51 (the first pipe part). Further, the pipe part F522 has the other end connected to the through hole 124 a of the intermediate-pressure turbine 12. A connection point J522 is provided at a position between the one end and the other end of the pipe part F522. In the pipe part F522, the automatic valve M522 is disposed at a position between the one end and the connection point J522. Further, the manual valve V522 is disposed at a position between the other end and the connection point J522 of the pipe part F522.

The pipe part F523 (an eighth pipe part) has one end connected to the connection point J51 a provided at the position closest to the one end side of the pipe part F51 (the first pipe part). Further, the pipe part F523 has the other end connected to the through hole 123 a of the intermediate-pressure turbine 12. A connection point J523 is provided at a position between the one end and the other end of the pipe part F523. The automatic valve M523 is disposed at a position between the one end and the connection point J523 of the pipe part F523. Further, the manual valve V523 is disposed at a position between the other end and the connection point J523 of the pipe part F523.

The pipe part F524 (a ninth pipe part) has one end connected to the connection point J522 of the pipe part F522 (the seventh pipe part). Further, the pipe part F524 has the other end connected to the through hole 124 b of the intermediate-pressure turbine 12. The manual valve V524 is disposed at a position between the one end and the other end of the pipe part F524.

The pipe part F525 (a tenth pipe part) has one end connected to the connection point J523 of the pipe part F523 (the eighth pipe part). Further, the pipe part F525 has the other end connected to the through hole 123 b of the intermediate-pressure turbine 12. The manual valve V525 is disposed at a position between the one end and the other end of the pipe part F525.

The pipe part F13 a (an eleventh pipe part) has one end connected to the steam discharge part 132 a of the first low-pressure turbine 13. Further, the pipe part F13 a has the other end connected to the connection point J514 a provided at the position closest to the one end side of the pipe part F514 (the fifth pipe part). The manual valve V13 a is disposed at a position between the one end and the other end of the pipe part F13 a.

The pipe part F13 b (a twelfth pipe part) has one end connected to the steam discharge part 132 b of the first low-pressure turbine 13. Further, the pipe part F13 b has the other end connected to the connection point J514 b provided at the second position from the one end side of the pipe part F514 (the fifth pipe part). The manual valve V13 b is disposed at a position between the one end and the other end of the pipe part F13 b.

The pipe part F14 a (a thirteenth pipe part) has one end connected to the steam discharge part 142 a of the second low-pressure turbine 14. Further, the pipe part F14 a has the other end connected to the connection point J514 c provided at the third position from the one end side of the pipe part F514 (the fifth pipe part). The manual valve V14 a is disposed at a position between the one end and the other end of the pipe part F14 a.

The pipe part F14 b (a fourteenth pipe part) has one end connected to the steam discharge part 142 b of the second low-pressure turbine 14. Further, the pipe part F14 b has the other end connected to the connection point J514 d provided at the position closest to the other end side of the pipe part F514 (the fifth pipe part). The manual valve V14 b is disposed at a position between the one end and the other end of the pipe part F14 b.

Although details will be described later, in the cooling air pipe system 512, the pipe part F51 (first cooling air supply part) is used when supplying the cooling air to the inner part of the inner casing 201 in the turbine casing 110 of the high-pressure turbine 11. Each of the pipe parts F511 and F512 (second cooling air supply part) is used for supplying the cooling air to the space between the inner casing 201 and the outer casing 202 in the turbine casing 110 of the high-pressure turbine 11.

In the cooling air pipe system 512, the pipe part F521 (first cooling air supply part) is used when supplying the cooling air to the inner part of the inner casing in the turbine casing of the intermediate-pressure turbine 12. Each of the pipe parts F522 to F525 (second cooling air supply part) is used for supplying the cooling air to the space between the inner casing and the outer casing in the turbine casing of the intermediate-pressure turbine 12.

Further, although the illustration is omitted, in the cooling air pipe system 512, each of the automatic valves M51, M511, and M521 to M523 is configured in a manner that it receives a control signal CTL52 output by the control unit 52, and its opening degree is automatically adjusted in accordance with the control signal CTL52. For example, each of the automatic valves M51, M511, and M521 to M523 includes an actuator, and the actuator varies a distance between a valve element and a valve seat in accordance with the control signal CTL52.

[A-2-1] Control Unit 52 (Controller)

In the turbine cooling apparatus 50, the control unit 52 is configured to control the operation of the cooling air supply unit 51 during the turning operation which is performed after the normal operation of the steam turbine is stopped. The control unit 52 includes an arithmetic unit (whose illustration is omitted) and a memory device (whose illustration is omitted), in which the arithmetic unit performs arithmetic processing by using a program stored in the memory device. Accordingly, the control unit 52 outputs the control signal CTL52 to each part of the cooling air supply unit 51, to thereby control the operation of each part.

Concretely, the control unit 52 outputs the control signal CTL52 to the air blowing section 511, thereby controlling the operation of the air blowing section 511. Further, the control unit 52 outputs the control signal CTL52 to the automatic valves M51, M511, and M521 to M523 of the cooling air pipe system 512, thereby controlling the operations of the automatic valves M51, M511, and M521 to M523.

As described above, the result of differential expansion and the result of temperature difference are input, as the actual measured data D10, to the control unit 52 from the steam turbine 10. Further, the control unit 52 uses the input actual measured data D10 to output the control signal CTL52.

[B] Operation

Hereinafter, explanation will be made on an operation when the turbine cooling apparatus 50 forcibly cools the steam turbine 10 during the turning operation which is performed after the normal operation of the steam turbine 10 is stopped.

When a forced cooling operation of forcibly cooling the steam turbine 10 is conducted, in the turbine cooling apparatus 50, the control unit 52 receives a command for performing the forced cooling operation, and outputs the control signal CTL52 to the cooling air supply unit 51. Subsequently, the cooling air supply unit 51 supplies, based on the control signal CTL52, cooling air to the inner part of the turbine casing of the steam turbine 10.

In the cooling air supply unit 51, the cooling air blown by the air blowing section 511 is supplied to the inner part of the turbine casing of the steam turbine 10 via the cooling air pipe system 512. In the cooling air pipe system 512, opening degrees of the plurality of automatic valves M51, M511, and M521 to M523 are adjusted based on the control signal CTL52, under the state where all of the plurality of manual valves V51, V511 and V512, V514, V521 to V525, V13 a, V13 b, V14 a, and V14 b are opened, resulting in that the cooling air flows through the plurality of pipe parts F51, F511 to F514, F521 to F525, F13 a, F13 b, F14 a, and F14 b. Note that through the pipe parts F13 a, F13 b, F14 a, and F14 b out of the above-described pipe parts, a part of the cooling air passed through the first low-pressure turbine 13 or the second low-pressure turbine 14 flows. The rest of the air flows to the steam condenser 60 after passing through the first low-pressure turbine 13 or the second low-pressure turbine 14, and is released to the outside via a vacuum break valve V60.

FIG. 4 is a flow chart illustrating an outline of the operation when the turbine cooling apparatus 50 cools the steam turbine 10 in the steam turbine system 1 according to the first embodiment.

[B-1] First Step (ST1)

As illustrated in FIG. 4, when performing the forced cooling operation of forcibly cooling the steam turbine 10, the supply of cooling air is first performed at a previously determined flow rate.

In the present embodiment, the previously determined flow rate corresponds to a flow rate determined by performing numerical calculation in advance so that the respective parts of the steam turbine 10 are set to have optimum states. Concretely, the previously determined flow rate corresponds to a flow rate determined by numerical calculation so that the differential expansion between the turbine rotor (indicated by reference numeral 300 in FIG. 2 or the like) and the turbine casing (indicated by reference numeral 110 in FIG. 2 or the like) in the steam turbine 10, and the temperature difference between the inner part of the steam chamber positioned at the entrance of the steam flow path through which the steam flows, in the inner part of the turbine casing (indicated by reference numeral 110 in FIG. 2 or the like) of the steam turbine 10 and the outer part of the steam chamber, fall within set ranges during a predetermined period of time.

In the present step, the control unit 52 controls the operation of the cooling air supply unit 51 so that the cooling air supply unit 51 supplies the cooling air to the steam turbine 10 at the previously determined flow rate for the predetermined period of time (refer to FIG. 1). Specifically, in the cooling air supply unit 51, the control unit 52 adjusts the opening degree of each of the plurality of automatic valves M51, M511, and M521 to M523, to thereby distribute and supply the cooling air at the previously determined flow rate to the respective parts of the steam turbine 10.

In the present embodiment, the turbine cooling apparatus 50 supplies the cooling air at the previously determined flow rate to the high-pressure turbine 11, to thereby cool the high-pressure turbine 11.

In this case, in the cooling air supply unit 51, the cooling air blown by the air blowing section 511 flows through the pipe part F51 of the cooling air pipe system 512, and then flows into the steam introducing parts 111 a and 111 b of the high-pressure turbine 11 via the main steam pipes F30 a and F30 b. The cooling air flows into the steam introducing parts 111 a and 111 b at the previously determined flow rate, with the use of the automatic valve M51 (refer to FIG. 1). The cooling air flowed into the steam introducing parts 111 a and 111 b flows through the inner part of the inner casing 201 in the turbine casing 110, and then is discharged to the outside from the steam discharge part 112 (refer to FIG. 2). Specifically, the cooling air at the previously determined flow rate is supplied to the steam flow path through which the steam flows as the working medium in the turbine casing 110 of the high-pressure turbine 11.

Along with this, the cooling air blown by the air blowing section 511 flows through the plurality of pipe parts F51, F511, and F512 of the cooling air pipe system 512, and then flows into the inner part of the high-pressure turbine 11 via the through holes 113 a and 113 b formed on the high-pressure turbine 11. The cooling air flows into the inner part of the high-pressure turbine 11, via the through holes 113 a and 113 b, at the previously determined flow rate with the use of the automatic valve M511 (refer to FIG. 1). The first tubular body 250 a and the second tubular body 250 b are disposed in the through holes 113 a and 113 b of the high-pressure turbine 11, and the cooling air flows into the space between the inner casing 201 and the outer casing 202 via the cooling air releasing ports H250 a formed on the first tubular body 250 a and the cooling air releasing ports H250 b formed on the second tubular body 250 b (refer to FIG. 2). Subsequently, the cooling air flows through the space between the inner casing 201 and the outer casing 202, and then is discharged to the outside from the steam discharge part 112. Specifically, the cooling air at the previously determined flow rate is supplied to the space positioned outside the steam flow path, in the inner part of the turbine casing 110 which forms the high-pressure turbine 11.

The cooling air discharged from the steam discharge part 112 of the high-pressure turbine 11 flows through the low-temperature reheat steam pipe F11. A part of the cooling air which flows through the low-temperature reheat steam pipe F11 is released to the outside, and the other part of the cooling air flows to the pipe part F513 from the connection point J11. The cooling air which flows through the pipe part F513 flows to the pipe part F514 from the connection point J513. The cooling air which flows through the pipe part F514 is released to the outside.

Other than the above, in the present embodiment, the turbine cooling apparatus 50 supplies the cooling air at the previously determined flow rate to the intermediate-pressure turbine 12, to thereby cool the intermediate-pressure turbine 12. The cooling air supplied to the intermediate-pressure turbine 12 is discharged to each of the first low-pressure turbine 13 and the second low-pressure turbine 14, resulting in that the first low-pressure turbine 13 and the second low-pressure turbine 14 are cooled.

In this case, in the cooling air supply unit 51, the cooling air blown by the air blowing section 511 flows through the plurality of pipe parts F51 and F521 of the cooling air pipe system 512, and then flows into the steam introducing part 121 of the intermediate-pressure turbine 12 via the high-temperature reheat steam pipe F40. The cooling air flows into the steam introducing part 121 at the previously determined flow rate, with the use of the automatic valve M521 (refer to FIG. 1). Although the illustration is omitted, the cooling air flowed into the steam introducing part 121 flows through the inner part of the inner casing in the turbine casing, and then is discharged to the outside from the steam discharge parts 122 a and 122 b (refer to FIG. 1). Specifically, the cooling air at the previously determined flow rate is supplied to the steam flow path through which the steam flows as the working medium, in the turbine casing of the intermediate-pressure turbine 12.

Along with this, the cooling air blown by the air blowing section 511 flows through the plurality of pipe parts F51, and F522 to F525 of the cooling air pipe system 512, and then flows into the inner part of the intermediate-pressure turbine 12 via the through holes 123 a, 124 a, 123 b, and 124 b formed on the intermediate-pressure turbine 12. The cooling air flows into the inner part of the intermediate-pressure turbine 12, via the through holes 123 a, 124 a, 123 b, and 124 b, at the previously determined flow rate with the use of the automatic valves M522 and M523 (refer to FIG. 1). Although the illustration is omitted, the cooling air flowed into the through holes 123 a, 124 a, 123 b, and 124 b flows into the space between the inner casing and the outer casing which form the turbine casing (refer to FIG. 2). Subsequently, the cooling air flows through the space between the inner casing and the outer casing, and then is discharged to the outside from the steam discharge parts 122 a and 122 b. Specifically, the cooling air at the previously determined flow rate is supplied to the space positioned outside the steam flow path, in the inner part of the turbine casing which forms the intermediate-pressure turbine 12.

The cooling air discharged from the steam discharge parts 122 a and 122 b of the intermediate-pressure turbine 12 flows through the crossover pipes F12 a, F12 b, and F12 c. The cooling air which flows through the crossover pipes F12 a, F12 b, and F12 c flows into the inner part of each of the first low-pressure turbine 13 and the second low-pressure turbine 14. Further, the cooling air flows through the inner part of each of the first low-pressure turbine 13 and the second low-pressure turbine 14, and then is discharged from the steam discharge parts 132 a and 132 b of the first low-pressure turbine 13, and the steam discharge parts 142 a and 142 b of the second low-pressure turbine 14.

A part of the cooling air discharged from the steam discharge parts 132 a and 132 b of the first low-pressure turbine 13 flows through the pipe parts F13 a and F13 b, and then flows into the pipe part F514 from the connection points J514 a and J514 b. In a similar manner, a part of the cooling air discharged from the steam discharge parts 142 a and 142 b of the second low-pressure turbine 14 flows through the pipe parts F14 a and F14 b, and then flows into the pipe part F514 from the connection points J514 c and J514 d. Further, the cooling air which flows through the pipe part F514 is released to the outside.

[B-2] Second Step (ST2)

Next, the flow rate of the cooling air is adjusted in accordance with the actual measured data, as illustrated in FIG. 4 (ST2).

Here, the control unit 52 controls the operation of the cooling air supply unit 51 based on the result obtained by measuring the differential expansion between the turbine rotor (indicated by reference numeral 300 in FIG. 2 or the like) and the turbine casing (indicated by reference numeral 110 in FIG. 2 or the like) in the steam turbine 10. Along with this, the control unit 52 controls the operation of the cooling air supply unit 51 based on the result obtained by measuring the temperature difference between the inner part of the steam chamber positioned at the entrance of the steam flow path through which the steam flows, in the inner part of the turbine casing (indicated by reference numeral 110 in FIG. 2 or the like) of the steam turbine 10 and the outer part of the steam chamber. For example, the control unit 52 controls the operation of the cooling air supply unit 51 by using a look-up table in which the above-described differential expansion and temperature difference, and the flow rate are associated with each other.

Concretely, when, based on the measurement result of the differential expansion described above, the turbine rotor 300 of the high-pressure turbine 11 is longer than the set range, the opening degree of the automatic valve M511 is adjusted so that the flow rate of the cooling air which flows through the pipe part F511 decreases. Specifically, the flow rate of the cooling air is adjusted so that a state where a temperature of the turbine casing 110 is lower than a temperature of the turbine rotor 300, turns into a state where the temperatures of the both are close to each other.

When, based on the result of the differential expansion described above, the turbine rotor 300 of the high-pressure turbine 11 is shorter than the set range, the opening degree of the automatic valve M51 is adjusted so that the flow rate of the cooling air which flows through the pipe part F51 decreases. Specifically, the flow rate of the cooling air is adjusted so that a state where the temperature of the turbine rotor 300 is lower than the temperature of the turbine casing 110, turns into a state where the temperatures of the both are close to each other.

Further, when, based on the result of the temperature difference described above, the temperature of the inner peripheral surface is lower than the temperature of the outer peripheral surface, the opening degree of the automatic valve M51 is adjusted so that the flow rate of the cooling air which flows through the pipe part F51 decreases. Specifically, the flow rate of the cooling air is adjusted so that a state where the temperature of the turbine rotor 300 is lower than the temperature of the turbine casing 110, turns into a state where the temperatures of the both are close to each other.

The flow rate of the cooling air is adjusted also in the intermediate-pressure turbine 12, in a similar manner to the high-pressure turbine 11.

[C] Summary (Operations, Effects, and the Like)

As described above, in the present embodiment, the turbine cooling apparatus 50 includes the cooling air supply unit 51, and the control unit 52 controlling the operation of the cooling air supply unit 51 during the turning operation. The control unit 52 controls the operation of the cooling air supply unit 51 so that the cooling air supply unit 51 supplies the cooling air at the previously determined flow rate, in the first step (ST1). Accordingly, in the present embodiment, the cooling is performed so that the states of the respective parts of the steam turbine 10 become close to the optimum states, in the first step (ST1).

Thereafter, in the present embodiment, the control unit 52 controls the operation of the cooling air supply unit 51, in the second step (ST2), based on the result obtained by measuring the differential expansion between the turbine rotor (indicated by reference numeral 300 in FIG. 2 or the like) and the turbine casing (indicated by reference numeral 110 in FIG. 2 or the like), and the result obtained by measuring the temperature difference between the inner peripheral surface of the steam chamber positioned at the entrance of the steam flow path through which the steam flows, in the turbine casing (indicated by reference numeral 110 in FIG. 2 or the like) and the outer peripheral surface of the steam chamber. Accordingly, in the present embodiment, it is possible to design such that when the above-described differential expansion and the above-described temperature difference do not fall within the previously determined ranges in the first step, the above-described differential expansion and the above-described temperature difference are set to fall within the previously determined ranges in the second step.

Therefore, in the present embodiment, it is possible to cool the steam turbine 10 in a short period of time, and it is possible to create a state where the above-described differential expansion and the above-described temperature difference fall within the previously determined ranges. Although an alarm is issued when the above-described differential expansion and the above-described temperature difference are out of the predetermined ranges, the issuance of the alarm can be prevented in the present embodiment.

Further, the turbine cooling apparatus 50 of the present embodiment is configured to make the cooling air flow along the rotation axis AX of the turbine rotor 300 in the space between the inner casing 201 and the outer casing 202. Concretely, as described above, there are provided the first tubular body 250 a and the second tubular body 250 b extending along the radial direction of the turbine rotor 300. The first tubular body 250 a and the second tubular body 250 b include the cooling air releasing ports H250 a and H250 b which penetrate so as to be along the rotation axis AX of the turbine rotor 300, so that the cooling air flows from the cooling air releasing ports H250 a and H250 b to the space between the inner casing 201 and the outer casing 202 (refer to FIG. 2). For this reason, in the present embodiment, it is possible to reduce the temperature difference between the inner part and the outer part of the inner casing 201, so that it is possible to solve the problem regarding the thermal stress of the inner casing 201, and at the same time, it is possible to efficiently cool the steam turbine 10.

Other than the above, in the present embodiment, the first tubular body 250 a is the balance plug attachment tube to which the balance plug (whose illustration is omitted) is attached. Further, the second tubular body 250 b is the thermocouple protection tube which houses the thermocouples (whose illustration is omitted) in the inner part thereof. The first tubular body 250 a has the cooling air releasing ports H250 a formed thereon, and the second tubular body 250 b has the cooling air releasing ports H250 b formed thereon. Accordingly, in the present embodiment, it is possible to realize the supply of cooling air through simple processing.

[D] Modified Example

Although the above-described embodiment describes the case where the operation of the cooling air supply unit 51 is controlled based on both of the result obtained by measuring the differential expansion between the turbine rotor (indicated by reference numeral 300 in FIG. 2 or the like) and the turbine casing (indicated by reference numeral 110 in FIG. 2 or the like), and the result obtained by measuring the temperature difference between the inner peripheral surface of the steam chamber positioned at the entrance of the steam flow path through which the steam flows, in the turbine casing (indicated by reference numeral 110 in FIG. 2 or the like) and the outer peripheral surface of the steam chamber, in the second step (ST2), the present invention is not limited to this. It is also possible to configure such that the operation of the cooling air supply unit 51 is controlled in accordance with at least either of the above-described differential expansion and the above-described temperature difference.

Although the above-described embodiment describes the case where, in the high-pressure turbine 11, the cooling air flowed through the space between the inner casing 201 and the outer casing 202 does not join with the cooling air which flows through the inner part of the inner casing 201, and is exhausted from the high-pressure turbine 11, the present invention is not limited to this. It is also possible that the high-pressure turbine 11 is configured such that the cooling air flowed through the space between the inner casing 201 and the outer casing 202 joins with the cooling air which flows through the inner part of the inner casing 201, and then is exhausted from the high-pressure turbine 11.

Although the above-described embodiment describes the case where the operation of the cooling air supply unit 51 is controlled based on the temperature difference between the inner peripheral surface of the steam chamber positioned at the entrance of the steam flow path in which the turbine stages are disposed, in the inner part of the turbine casing 110 and the outer peripheral surface of the steam chamber, the present invention is not limited to this. It is also possible to configure such that the operation of the cooling air supply unit 51 is controlled based on a temperature difference between the upper half casing and the lower half casing.

Although the above-described present embodiment describes the case where the first tubular body 250 a is the balance plug attachment tube, and the second tubular body 250 b is the thermocouple protection tube, the present invention is not limited to this. It is also possible that the first tubular body 250 a is not used as the balance plug attachment tube. In a similar manner, it is also possible that the second tubular body 250 b is not used as the thermocouple protection tube.

Second Embodiment [A] Configuration

FIG. 5 is a view schematically illustrating a steam turbine system 1 according to a second embodiment. In FIG. 5, a flow path of cooling air supplied to a steam turbine 10 as a cooling medium is indicated by an arrow mark of solid line, in a similar manner to FIG. 1.

As illustrated in FIG. 5, in a cooling air supply unit 51 of the present embodiment, some manual valves V51, V511, V512, V521, V522, V523, V524, and V525 are not disposed in a cooling air pipe system 512, different from the first embodiment (refer to FIG. 1). Further, the number of automatic valves M51, M511, M512, and M521 to M525 is increased, when compared to the first embodiment (refer to FIG. 1). The present embodiment is similar to the first embodiment except for the above-described points and points related to the above-described points. Accordingly, description of parts in the present embodiment overlapped with the parts of the above-described embodiment will be omitted appropriately.

In the present embodiment, the automatic valves M51, M511, M512, and M521 to M525 are disposed on pipe parts F51, F511, F512, and F521 to F525, respectively, which are connected to a plurality of supply ports, respectively, to which cooling air is supplied in the steam turbine 10.

Concretely, the automatic valve M51 is disposed on the pipe part F51 (a first pipe part) at a position between the other end (a main steam pipe F30 a side) and a connection point J51 d provided at a position closest to the other end side.

The automatic valve M511 is disposed on the pipe part F511 (a second pipe part) at a position between the other end (a through hole 113 a side of a high-pressure turbine 11) and a connection point J511.

The automatic valve M512 is disposed on the pipe part F512 (a third pipe part) at a position between one end and the other end (a through hole 113 b side of the high-pressure turbine 11).

The automatic valve M521 is disposed on the pipe part F521 (a sixth pipe part) at a position between one end and the other end.

The automatic valve M522 is disposed on the pipe part F522 (a seventh pipe part) at a position between the other end (a through hole 124 a side of an intermediate-pressure turbine 12) and a connection point J522.

The automatic valve M523 is disposed on the pipe part F523 (an eighth pipe part) at a position between the other end (a through hole 123 a side of the intermediate-pressure turbine 12) and a connection point J523.

The automatic valve M524 is disposed on the pipe part F524 (an ninth pipe part) at a position between one end and the other end (a through hole 123 b side of the intermediate-pressure turbine 12).

The automatic valve M525 is disposed on the pipe part F525 (a tenth pipe part) at a position between one end and the other end (a through hole 124 b side of the intermediate-pressure turbine 12).

[B] Operation

In the present embodiment, when performing a forced cooling operation of forcibly cooling the steam turbine 10, at first, cooling air is supplied at a previously determined flow rate in a first step (ST1), in a similar manner to the first embodiment (refer to FIG. 4). Next, in a second step (ST2), adjustment regarding the flow rate of the cooling air is conducted in accordance with actual measured data (ST2).

In the second step (ST2), when, based on the result of the differential expansion described above, the turbine rotor 300 of the high-pressure turbine 11 is longer than the set range, the opening degree of each of the automatic valves M511 and M512 is adjusted so that the flow rate of the cooling air which flows through the pipe part F511 decreases, in a similar manner to the first embodiment.

On the contrary, when, based on the result of the differential expansion described above, the turbine rotor 300 of the high-pressure turbine 11 is shorter than the set range, the opening degree of the automatic valve M51 is adjusted so that the flow rate of the cooling air which flows through the pipe part F51 decreases.

Further, when, based on the result of the temperature difference described above, the temperature of the inner peripheral surface is lower than the temperature of the outer peripheral surface, the opening degree of the automatic valve M51 is adjusted so that the flow rate of the cooling air which flows through the pipe part F51 decreases.

The flow rate of the cooling air is adjusted also in the intermediate-pressure turbine 12, in a similar manner to the high-pressure turbine 11.

[C] Summary (Operations, Effects, and the Like)

In the present embodiment, different from the first embodiment, some manual valves V51, V511, V512, V521, V522, V523, V524, and V525 (refer to FIG. 1) are not disposed, but, there are disposed the automatic valves M51, M511, M512, M521, M522, M523, M524, and M525, which also fulfill the functions of the not-disposed manual valves. Accordingly, it is possible to easily realize the simplification of the apparatus.

In the present embodiment, the automatic valves M51, M511, M512, and M521 to M525 are disposed on the pipe parts F51, F511, F512, and F521 to F525, respectively, which are connected to the plurality of supply ports, respectively, to which the cooling air is supplied in the steam turbine 10, as described above. Accordingly, in the present embodiment, the cooling can be conducted more efficiently.

Third Embodiment [A] Configuration

FIG. 6 is a view schematically illustrating a steam turbine system 1 according to a third embodiment. In FIG. 6, a flow path of cooling air supplied to a steam turbine 10 as a cooling medium is indicated by an arrow mark of solid line, in a similar manner to FIG. 1.

FIG. 7 is a sectional view illustrating a high-pressure turbine 11 in the steam turbine system 1 according to the third embodiment. FIG. 7 illustrates a cross section of a vertical plane (xz plane) defined by a direction along a rotation axis AX (x direction) in the horizontal direction (x direction, y direction), and a vertical direction (z direction).

As illustrated in FIG. 6, the through hole 113 b is not provided in the high-pressure turbine 11 of the present embodiment (refer to FIG. 1). Further, the pipe part F512 and the manual valve V512 are not provided (refer to FIG. 1). Further, as illustrated in FIG. 7, the second tubular body 250 b is not provided (refer to FIG. 2). In the present embodiment, a cooling air supply unit 51 is provided with a cooling air releasing pipe 600, different from the first embodiment (refer to FIG. 2). The present embodiment is similar to the first embodiment except for the above-described points and points related to the above-described points. Accordingly, description of parts in the present embodiment overlapped with the parts of the above-described embodiment will be omitted appropriately.

In the present embodiment, the cooling air releasing pipe 600 is disposed in the inner part of the turbine casing 110 in the high-pressure turbine 11, as illustrated in FIG. 7.

FIG. 8 is a view illustrating the cooling air releasing pipe 600 and the first tubular body 250 a in the steam turbine system 1 according to the first embodiment. FIG. 8 illustrates a state where the pipe and the tubular body are seen from a direction along the rotation axis AX (x direction), in a similar manner to FIG. 3.

As illustrated in FIG. 8, the cooling air releasing pipe 600 is provided at a position between the inner casing 201 and the outer casing 202, in the inner part of the turbine casing 110. Here, the cooling air releasing pipe 600 has a ring shape, and is disposed so as to surround the outer peripheral surface of the inner casing 201.

As illustrated in FIG. 8, a plurality of cooling air releasing ports H600 releasing the cooling air, are formed on the cooling air releasing pipe 600. The plurality of cooling air releasing ports H600 are formed, so as to be arranged at equal intervals, in the periphery of the outer peripheral surface of the inner casing 201.

The cooling air releasing pipe 600 is connected, at an upper part thereof, to a lower end part of the first tubular body 250 a, and the cooling air which flows through the first tubular body 250 a is released from the plurality of cooling air releasing ports H600. The cooling air released from each of the plurality of cooling air releasing ports flows to the space between the inner casing 201 and the outer casing 202.

[B] Summary (Operations, Effects, and the Like)

As described above, in the present embodiment, the cooling air releasing pipe 600 is disposed. The cooling air releasing pipe 600 has the plurality of cooling air releasing ports H600 formed thereon so as to be arranged at equal intervals in the periphery of the outer peripheral surface of the inner casing 201. For this reason, in the present embodiment, it is possible to uniformly supply the cooling air to the space between the inner casing 201 and the outer casing 202.

Therefore, in the present embodiment, it is possible to cool the steam turbine 10 in a short period of time.

In particular, the present embodiment is suitable for a case where it is not possible to provide the through hole 113 b, and thus it is difficult to dispose the second tubular body 250 b in the high-pressure turbine 11.

<Others>

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions. 

What is claimed is:
 1. A turbine cooling apparatus for cooling a steam turbine having a turbine casing and a turbine rotor housed in an inner part of the turbine casing, the turbine cooling apparatus comprising: a cooling air supply unit configured to supply cooling air to the inner part of the turbine casing; and a control unit configured to control an operation of the cooling air supply unit during a turning operation, wherein the control unit controls the operation of the cooling air supply unit to make the cooling air supply unit supply the cooling air at a previously determined flow rate, and then controls the operation of the cooling air supply unit based on at least either of a result obtained by measuring differential expansion between the turbine rotor and the turbine casing, and a result obtained by measuring a temperature difference between an inner peripheral surface of a steam chamber positioned at an entrance of a steam flow path through which steam flows in the turbine casing and an outer peripheral surface of the steam chamber.
 2. The turbine cooling apparatus according to claim 1, wherein the turbine casing has: an inner casing housing the turbine rotor in an inner part thereof; and an outer casing housing the inner casing in an inner part thereof; the cooling air supply unit comprises: a first cooling air supply part configured to supply the cooling air to the inner part of the inner casing; and a second cooling air supply part configured to supply the cooling air to a space between the inner casing and the outer casing; and the control unit controls operations of the first cooling air supply part and the second cooling air supply part to make the first cooling air supply part and the second cooling air supply part supply the cooling air at a previously determined flow rate, and then controls the operations of the first cooling air supply part and the second cooling air supply part based on at least either of the result obtained by measuring the differential expansion, and the result obtained by measuring the temperature difference.
 3. The turbine cooling apparatus according to claim 2, wherein the turbine cooling apparatus is configured to make the cooling air supplied by the second cooling air supply part flow along a rotation axis of the turbine rotor, in the space between the inner casing and the outer casing.
 4. The turbine cooling apparatus according to claim 3, further comprising tubular bodies extending along a radial direction of the turbine rotor, wherein the tubular bodies include cooling air releasing ports penetrating to be along the rotation axis of the turbine rotor, and the cooling air supplied by the second cooling air supply part flows from the cooling air releasing ports to the space between the inner casing and the outer casing.
 5. The turbine cooling apparatus according to claim 4, wherein the tubular bodies comprise: a first tubular body; and a second tubular body, wherein the cooling air releasing ports are formed on each of the first tubular body and the second tubular body.
 6. The turbine cooling apparatus according to claim 3, further comprising a cooling air releasing pipe disposed to surround an outer peripheral surface of the inner casing, wherein a plurality of cooling air releasing ports releasing the cooling air are formed on the cooling air releasing pipe, the plurality of cooling air releasing ports are arranged, at equal intervals, in a periphery of the outer peripheral surface of the inner casing, and the cooling air supplied by the second cooling air supply part flows from each of the plurality of cooling air releasing ports to the space between the inner casing and the outer casing. 